1. The Field of Invention
The invention relates to a tire intended to bear heavy loads and inflated to very high pressure, greater than 12 bar, such as, for example, an aircraft tire.
2. The Related Art
U.S. Pat. No. 4,832,102 describes an aircraft tire comprising a crown, two sidewalls and two beads, a carcass reinforcement and a crown reinforcement, in which the carcass reinforcement comprises two circumferential alignments of reinforcing threads of high elasticity modulus anchored in the two beads. The crown reinforcement comprises at least one working block with at least one ply of reinforcing threads of high elasticity modulus. The carcass reinforcement is anchored in the beads by turning up, around a bead wire, the two circumferential alignments of first reinforcing threads of high elasticity modulus.
In what follows, “linear density” is understood to mean the weight in grams of one thousand meters of a reinforcing thread. The linear density is expressed in tex. The stress to which a reinforcing thread is subjected and the modulus of this reinforcing thread are expressed in “cN/tex”, cN meaning centinewton.
“Reinforcing thread” is understood to mean any reinforcement element in the form of a thread which is able to reinforce a given matrix, for example a rubber matrix. As reinforcing threads, mention will be made, for example, of multifilament yarns, these yarns possibly being twisted on themselves or not, unit threads such as single cords of high elementary diameter, with or without a twist on themselves, cabled yarns or plied yarns (“cords”) obtained by cabling or plying operations on such unit threads or yarns, such reinforcing threads possibly being hybrid ones, that is to say, composite ones, comprising elements of different natures.
“Plied yarn” (or “folded yarn”) is understood to mean a reinforcing thread formed of two single yarns or more assembled together by plying operations. Such single yarns, which are generally formed of multifilament yarns, are first of all plied individually in one direction (S or Z direction of twist) during a first plying stage, then twisted together in the opposite direction (Z or S direction of twist, respectively) during a second plying stage.
“Adherent reinforcing thread” is understood to mean a reinforcing thread which has undergone an appropriate coating treatment, referred to as sizing or adherization treatment, capable of making the reinforcing thread, after suitable heat treatment, adhere to the matrix for which it is intended.
“Axial” is understood to mean a direction parallel to the axis A of the tire. This direction may be “axially inner” when it is directed towards the inside of the tire and “axially outer” when it is directed towards the outside of the tire.
“Radial” is understood to mean a direction perpendicular to the axis A of the tire and passing through the axis A. This direction may be “radially inner” or “radially outer” depending on whether it is directed towards the axis A or towards the outside of the tire.
“Elasticity modulus” of a rubber mix is understood to mean a secant modulus of extension at 10% deformation and at ambient temperature.